The invention concerns a bearing arrangement for supporting a movable component, in particular the crankshaft of an internal combustion engine, having at least one bearing for receiving the component and an oil feed line to each bearing.
It is already conventional and has long been known to install filters in the oil circuit of internal combustion engines in order to keep contamination and impurities away from the bearings. Those filters are usually provided at a central location in the oil circuit and cannot entirely reliably prevent contamination and impurities reaching the bearing locations, in particular the original dirt which generally cannot be entirely avoided upon assembly. Hitherto therefore the practice has been to use bearing materials which were soft in a certain sense and which thus entailed an embedding capability for impurities in the oil so that the proper operability of the bearing was not seriously adversely affected.
The object of the invention is to provide an improved bearing arrangement in which even bearing materials which have a particularly sensitive reaction to impurities are used.
In accordance with the invention that is achieved in that a filter is arranged in the oil feed line directly upstream of the bearing. An engine generally has a plurality of bearings, for example crankshaft bearings. In accordance with a preferred embodiment of the invention the filter is not arranged in a common main oil line but a respective specific filter element is arranged just upstream of the respective bearing in the respective oil feed line thereto, which branches from the main oil line and leads to the respective bearing. Advantageously, the distance of the filter from the bearing is in the centimeter range and below. If the structure configuration allows it, it is desirable if the outlet of the filter is less than 5 mm from the bearing, that is to say it is disposed practically directly at the bearing. That means that the section in which potential impurities can occur is vanishingly short and any particles which may occur, in particular the original dirt which occurs upon assembly of the engine, are reliably kept away from the bearing location.
The invention is particularly suitable for plain bearings which have a hard coating which is applied galvanically or by sputtering and which is of a small thickness (preferably less than 50 xcexcm). Plain bearings of that kind are inexpensive to produce but hitherto they were not used because of their sensitivity to dirt. The filter arrangement according to the invention now makes it possible to resolve the contamination problem and it is also possible reliably to use directly coated plain bearings with a thin hard layer. The fineness of the filter can be adapted to the respective conditions involved, for example it is desirable to use filters which retain particles which are larger than 0.1 mm.
From the structural point of view, such a filter can be in the form of a so-called gap filter or edge filter in which the oil is passed through at least one gap defining the maximum particle size which is allowed to pass therethrough. In particular, such a gap filter may have an insert body which has V-shaped recesses. The entire insert body is then fitted into a receiving bore which is slightly larger in diameter than the insert body itself. The oil can then flow into a V-shaped recess and can flow by way of the gap between the outside surface of the insert body and the inside surface of the receiving bore into an adjacent V-shaped recess which is open towards the bearing. The V-shape provides that the flow speed by way of the gap is substantially the same at all locations. Gap filters of that kind are already structurally known per se, but hitherto they were only used upstream of injection nozzles in order to retain impurities from the fuel.